Source assessment of atmospheric fine particulate matter in a Chinese megacity: Insights from long-term, high-time resolution chemical composition measurements from Shanghai flagship monitoring supersite

Abstract Here we present a long-term, hourly resolution dataset (from January 2014 to April 2015) of secondary inorganic aerosol (SIA) matter, organic matter (OM) and black carbon (BC) as PM2.5 chemical components in China. Seasonally differentiated weekly diurnal profiles of major particulate species were investigated in conjunction with potential source contribution function (PSCF) analysis. The average concentration of PM2.5 was 48.3 ± 35.1 μg m−3, in which OM was the major constituent (29.7 ± 13.9%), followed by sulfate (25.1 ± 8.1%), nitrate (18.5 ± 8.3%), ammonium (13.3 ± 3.8%), and other trace species (6.8 ± 4.0%). Interestingly, unlike other PM species, OM concentrations kept very similar level among different seasons, indicating on-road traffic is a stable source of PM2.5. Besides, a persistently strong particulate OM pollution belt was found along the lower reaches of Yangtze River. Significant enhancement of SIA (mainly nitrate) was coincided with high PM2.5 mass loading. Source apportionment were conducted and found the overwhelming dominance of long-range transport of the pollutants from north China. Using a case study, we further integrate Weather Research and Forecasting (WRF) meteorological modeling and lidar observation to better understand the evolution process of a typical pollution episode. Our assessment of the extremely large datasets derived from Shanghai supersite demonstrated the online instrumentation as a robust and credible alternative to filter-based sampling techniques for long-term PM2.5 monitoring and characterization in heavily polluted areas.